In 2012, south central Kansas endured bone-dry conditions throughout May, a month when ample rains usually wash over the region (3.80 inches/96.52 millimeters on average). By May 29, Wichita had recorded just 0.63 inches (16.00 millimeters) of rain, putting the city on track for its second driest May on record.
But on May 30, the dry spell ended in dramatic fashion. The three key ingredients for thunderstorms—humid air, atmospheric instability, and convection—came together in the afternoon to create fierce storms. Around 3 p.m., storms began to develop in large numbers north and west of the city. By 5 p.m., a band of intense storms had formed a squall line, which forecasters warned could turn into a derecho. The system was racing south toward Wichita at up to 70 miles (110 kilometers) per hour, dumping torrential rains and hail the size of ping-pong balls.
The leading edge was approaching Kechi, a small city 10 miles north of Wichita, when storm-chasing photographer Brian Johnson captured the images he used to stitch together this ominous view of the approaching weather (top image). The panorama view shows a low-elevation, wedge-shaped cloud known as a shelf cloud forming over a freshly-cut wheat field. Shelf clouds (a type of arcus cloud) often have damaging winds underneath them and form just ahead of squall lines in an area called the gust front.
On the same day, the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA’s Aqua satellite was orbiting 438 miles (705 kilometers) overhead. A few hours before Johnson snapped his photographs, MODIS acquired this (bottom) view of the developing storm system.The large white cloud in the upper part of the image is one of the numerous storm clouds that billowed up over the area that afternoon as warm, moist air from the surface rose rapidly toward the stratosphere. (Watch this animation to see the storm clouds evolve over time).
“There is an open farm field roughly two miles from my house...I sat there for about 20 minutes before this large squall line pushed through the clouds,” Johnson wrote on a blog that chronicles his storm chasing. “I was hit with a pretty good gust front as it got closer, but as the winds increased, I decided to get to shelter. This photo was one of the last ones I took.“